--- 1/draft-ietf-mip6-location-privacy-ps-05.txt 2007-02-21 17:12:24.000000000 +0100
+++ 2/draft-ietf-mip6-location-privacy-ps-06.txt 2007-02-21 17:12:24.000000000 +0100
@@ -1,515 +1,485 @@
+
MIP6 Working Group Rajeev Koodli
-INTERNET DRAFT Nokia Research Center
-Informational
-2 February 2007
+Internet-Draft Nokia Research Center
+Intended status: Informational February 19, 2007
+Expires: August 23, 2007
IP Address Location Privacy and Mobile IPv6: Problem Statement
- draft-ietf-mip6-location-privacy-ps-05.txt
+ draft-ietf-mip6-location-privacy-06.txt
+
+Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering
- Task Force (IETF), its areas, and its working groups. Note
- that other groups may also distribute working documents as
- Internet-Drafts.
+ Task Force (IETF), its areas, and its working groups. Note that
+ other groups may also distribute working documents as Internet-
+ Drafts.
- Internet-Drafts are draft documents valid for a maximum of
- six months and may be updated, replaced, or obsoleted by other
- documents at any time. It is inappropriate to use Internet-Drafts
- as reference material or to cite them other than as "work in
- progress."
+ Internet-Drafts are draft documents valid for a maximum of six months
+ and may be updated, replaced, or obsoleted by other documents at any
+ time. It is inappropriate to use Internet-Drafts as reference
+ material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
- This document is a submission of the IETF MIP6 WG. Comments should
- be directed to the MIP6 WG mailing list, mip6@ietf.org.
-
- Abstract
-
- In this document, we discuss Location Privacy as applicable to
- Mobile IPv6. We document the concerns arising from revealing Home
- Address to an on-looker and from disclosing Care of Address to a
- correspondent.
-
- Contents
-
-Abstract i
-
- 1. Introduction 1
-
- 2. Definitions 3
-
- 3. Problem Definition 4
- 3.1. Disclosing the Care-of Address to the Correspondent Node 4
- 3.2. Revealing the Home Address to On-lookers . . . . . . . 4
- 3.3. Problem Scope . . . . . . . . . . . . . . . . . 4
-
- 4. Problem Illustration 5
-
- 5. Conclusion 8
-
- 6. IANA Considerations 8
-
- 7. Security Considerations 8
-
- 8. Acknowledgment 9
-
- 9. References 9
- 9.1. Normative References . . . . . . . . . . . . . . 9
- 9.2. Informative References . . . . . . . . . . . . . 9
+ This Internet-Draft will expire on August 23, 2007.
-10. Author's Address 10
+Copyright Notice
- A. Background 11
+ Copyright (C) The IETF Trust (2007).
-Intellectual Property Statement 12
+Abstract
-Disclaimer of Validity 12
+ In this document, we discuss Location Privacy as applicable to Mobile
+ IPv6. We document the concerns arising from revealing Home Address
+ to an on-looker and from disclosing Care of Address to a
+ correspondent.
-Copyright Statement 13
+Table of Contents
-Acknowledgment 13
+ 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
+ 2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 4
+ 3. Problem Definition . . . . . . . . . . . . . . . . . . . . . . 5
+ 3.1. Disclosing the Care-of Address to the Correspondent
+ Node . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
+ 3.2. Revealing the Home Address to On-lookers . . . . . . . . . 5
+ 3.3. Problem Scope . . . . . . . . . . . . . . . . . . . . . . 5
+ 4. Problem Illustration . . . . . . . . . . . . . . . . . . . . . 6
+ 5. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 8
+ 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
+ 7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
+ 8. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . 9
+ 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
+ 9.1. Normative References . . . . . . . . . . . . . . . . . . . 9
+ 9.2. Informative References . . . . . . . . . . . . . . . . . . 9
+ Appendix A. Background . . . . . . . . . . . . . . . . . . . . . 10
+ Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10
+ Intellectual Property and Copyright Statements . . . . . . . . . . 11
1. Introduction
- The problems of location privacy, and privacy when using IP
- for communication have become important. IP privacy is broadly
- concerned with protecting user communication from unwittingly
- revealing information that could be used to analyze and gather
- sensitive user data. Examples include gathering data at certain
- vantage points, collecting information related to specific traffic,
- and monitoring (perhaps) certain populations of users for activity
- during specific times of the day, etc. In this document, we refer
- to this as the "profiling" problem.
+ The problems of location privacy, and privacy when using IP for
+ communication have become important. IP privacy is broadly concerned
+ with protecting user communication from unwittingly revealing
+ information that could be used to analyze and gather sensitive user
+ data. Examples include gathering data at certain vantage points,
+ collecting information related to specific traffic, and monitoring
+ (perhaps) certain populations of users for activity during specific
+ times of the day, etc. In this document, we refer to this as the
+ "profiling" problem.
- Location privacy is concerned with the problem of revealing
- roaming, which we define here as the process of a Mobile Node
- (MN) moving from one network to another with or without on-going
- sessions. A constant identifier with global scope can reveal
- roaming. Examples are a device identifier such as an IP address,
- and a user identifier such as a SIP [9] URI [2]. Often, a binding
- between these two identifiers is available, e.g., through DNS [5].
- Traffic analysis of such IP and Upper Layer Protocol identifiers
- on single network can indicate device and user roaming. Roaming
- could also be inferred by means of profiling constant fields in IP
- communication across multiple network movements. For example, an
- Interface Identifier (IID) [10 ] in the IPv6 address that remains
- unchanged across networks could suggest roaming. The SPI in the
- IPsec [4] header is another field that may be subject to such
+ Location privacy is concerned with the problem of revealing roaming,
+ which we define here as the process of a Mobile Node (MN) moving from
+ one network to another with or without on-going sessions. A constant
+ identifier with global scope can reveal roaming. Examples are a
+ device identifier such as an IP address, and a user identifier such
+ as a SIP [rfc3261] URI[rfc2396]. Often, a binding between these two
+ identifiers is available, e.g., through DNS [rfc1035]. Traffic
+ analysis of such IP and Upper Layer Protocol identifiers on single
+ network can indicate device and user roaming. Roaming could also be
+ inferred by means of profiling constant fields in IP communication
+ across multiple network movements. For example, an Interface
+ Identifier (IID) [rfc2462] in the IPv6 address that remains unchanged
+ across networks could suggest roaming. The SPI in the IPsec
+ [rfc4301] header is another field that may be subject to such
profiling and inference. Inferring roaming in this way typically
requires traffic analysis across multiple networks, or colluding
attackers, or both. When location privacy is compromised, it could
lead to more targetted profiling of user communication.
- As can be seen, the location privacy problem spans multiple
- protocol layers. Nevertheless, it is important to understand and
- specify the problem as applicable to concerned protocols in order
- to at least mitigate the effects of the problem. In this context,
- it is particularly important to Mobile IP, which defines a global
- identifier (Home Address) that can reveal device roaming, and in
- conjunction with a corresponding user identifier (such as a SIP
- URI), can also reveal user roaming. Furthermore, a user may not
- wish to reveal roaming to correspondent(s), which translates to the
- use of Care-of Address. As with Home Address, the Care-of Address
- can also reveal the topological location of the Mobile Node.
+ As can be seen, the location privacy problem spans multiple protocol
+ layers. Nevertheless, we can examine problems encountered by nodes
+ using a particular protocol layer. Roaming is particularly important
+ to Mobile IP, which defines a global identifier (Home Address) that
+ can reveal device roaming, and in conjunction with a corresponding
+ user identifier (such as a SIP URI), can also reveal user roaming.
+ Furthermore, a user may not wish to reveal roaming to
+ correspondent(s), which translates to the use of Care-of Address. As
+ with Home Address, the Care-of Address can also reveal the
+ topological location of the Mobile Node.
- This document describes the concerns arising from the use of Home
- Address from a visited network. This document also outlines the
- considerations in disclosing a Care-of Address. This document
- is primarily concerned with the vulnerabilities arising from
- possible traffic analysis along the MN - CN path and the MN - HA
- path, where the disclosure of Mobile IP addresses is sufficient to
- reveal roaming. This document does not consider inferring roaming
- from profiling fields such as an IID or an SPI for the following
- reasons: First, such inference could be done independently, so the
- problem is not specific to Mobile IP. Second, with Mobile IP, it
- is sufficient to simply monitor the usage of Home Address from a
- single visited network in order to deduce roaming. In other words,
- the attackers need not conduct traffic profiling across multiple
- networks, or collude with each other, or do both in order to infer
- roaming when Mobile IP is used. Hence, we limit the scope of this
- document to revealing the Mobile IP addresses.
+ This document scopes the problem of location privacy for the Mobile
+ IP protocol. The primary goal is to prevent attackers on the path
+ between the Mobile Node (MN) and the Correspondent Node (CN) from
+ detecting roaming due to the disclosure of the Home Address. The
+ attackers are assumed to be able to observe, modify and inject
+ traffic at one point between the MN and the CN. The attackers are
+ assumed not to be able to observe at multiple points and correlate
+ observations to detect roaming. For this reason, MAC addresses, IIDs
+ and other fields which can be profiled to detect roaming are only in
+ scope to the extent that they can be used by an attacker at one
+ point. Upper layer protocol identifiers that expose roaming are out
+ of scope except that a solution to the problem described here needs
+ to be usable as a building block in solutions to those problems.
- This document is only concerned with IP Address Location Privacy
- in the context of Mobile IPv6. It does not address the overall
- privacy problem. For instance, it does not address privacy
- issues related to MAC addresses or the relationship of IP and MAC
- addresses [3], or the Upper Layer Protocol addresses. Solution
- to the problem specified here should provide protection against
- roaming disclosure due to using Mobile IPv6 addresses from a
- visited network.
+ This document also considers the problem from the exposure of Care-of
+ Address to the CN.
+
+ This document is only concerned with IP Address Location Privacy in
+ the context of Mobile IPv6. It does not address the overall privacy
+ problem. For instance, it does not address privacy issues related to
+ MAC addresses or the relationship of IP and MAC addresses
+ [draft-haddad], or the Upper Layer Protocol addresses. Solution to
+ the problem specified here should provide protection against roaming
+ disclosure due to using Mobile IPv6 addresses from a visited network.
This document assumes that the reader is familiar with the basic
- operation of Mobile IPv6 [1] and the associated terminology defined
- therein. For convenience, we provide some definitions below.
+ operation of Mobile IPv6 [rfc3775] and the associated terminology
+ defined therein. For convenience, we provide some definitions below.
2. Definitions
- - Mobile Node (MN): A Mobile IPv6 Mobile Node that freely roams
+ o Mobile Node (MN): A Mobile IPv6 Mobile Node that freely roams
around networks
-
- - Correspondent Node (CN): A Mobile IPv6 that node corresponds
- with a MN
-
- - Home Network: The network where the MN is normally present
- when it is not roaming
-
- - Visited Network: A network which a MN uses to access Internet
- when it is roaming
-
- - Home Agent: A router on the MN's home network which provides
+ o Correspondent Node (CN): A Mobile IPv6 that node corresponds with
+ a MN
+ o Home Network: The network where the MN is normally present when it
+ is not roaming
+ o Visited Network: A network which a MN uses to access Internet when
+ it is roaming
+ o Home Agent: A router on the MN's home network which provides
forwarding support when the MN is roaming
-
- - Home Address (HoA): The MN's unicast IP address valid on its
- home network
-
- - Care-of Address (CoA): The MN's unicast IP address valid on the
+ o Home Address (HoA): The MN's unicast IP address valid on its home
+ network
+ o Care-of Address (CoA): The MN's unicast IP address valid on the
visited network
-
- - Reverse Tunneling or Bidirectional Tunneling: A mechanism used
- for packet forwarding between the MN and its Home Agent
-
- - Route Optimization: A mechanism which allows direct routing
- of packets between a roaming MN and its CN, without having to
+ o Reverse Tunneling or Bidirectional Tunneling: A mechanism used for
+ packet forwarding between the MN and its Home Agent
+ o Route Optimization: A mechanism which allows direct routing of
+ packets between a roaming MN and its CN, without having to
traverse the home network.
3. Problem Definition
3.1. Disclosing the Care-of Address to the Correspondent Node
- When a Mobile IP MN roams from its home network to a visited
- network or from one visited network to another, use of Care-of
- Address in communication with a correspondent reveals that the
- MN has roamed. This assumes that the correspondent is able to
- associate the Care-of Address to Home Address, for instance by
- inspecting the Binding Cache Entry. The Home Address itself is
- assumed to have been obtained by whatever means (e.g., through DNS
- lookup).
+ When a Mobile IP MN roams from its home network to a visited network
+ or from one visited network to another, use of Care-of Address in
+ communication with a correspondent reveals that the MN has roamed.
+ This assumes that the correspondent is able to associate the Care-of
+ Address to Home Address, for instance by inspecting the Binding Cache
+ Entry. The Home Address itself is assumed to have been obtained by
+ whatever means (e.g., through DNS lookup).
3.2. Revealing the Home Address to On-lookers
- When a Mobile IP MN roams from its home network to a visited
- network or from one visited network to another, use of Home Address
- in communication reveals to an on-looker that the MN has roamed.
- When a binding of Home Address to a user identifier (such as
- a SIP URI) is available, the Home Address can be used to also
- determine that the user has roamed. This problem is independent
- of whether the MN uses Care-of Address to communicate directly
- with the correspondent (i.e., uses route optimization), or the MN
- communicates via the Home Agent (i.e., uses reverse tunneling).
-
- Location privacy may be compromised if an on-looker is present
- on the MN - HA path (when bidirectional tunneling is used), or
- when the on-looker is present on the MN and CN path (when route
- optimization is used).
+ When a Mobile IP MN roams from its home network to a visited network
+ or from one visited network to another, use of Home Address in
+ communication reveals to an on-looker that the MN has roamed. When a
+ binding of Home Address to a user identifier (such as a SIP URI) is
+ available, the Home Address can be used to also determine that the
+ user has roamed. This problem is independent of whether the MN uses
+ Care-of Address to communicate directly with the correspondent (i.e.,
+ uses route optimization), or the MN communicates via the Home Agent
+ (i.e., uses reverse tunneling). Location privacy can be compromised
+ when an on-looker is present on the MN - CN path (when route
+ optimization is used). It may also be compromised when the on-looker
+ is present on the MN - HA path (when bidirectional tunneling without
+ encryption is used. See below).
3.3. Problem Scope
- With existing Mobile IPv6 solutions, there is some protection
- against location privacy. If a Mobile Node uses reverse tunneling
- with ESP encryption, then the Home Address is not revealed on
- the MN - HA path. So, eavesdroppers on the MN - HA path cannot
- determine roaming. They could, however, still profile fields in
- the ESP header; however, this problem is not specific to Mobile
- IPv6 location privacy.
+ With existing Mobile IPv6 solutions, there is some protection against
+ location privacy. If a Mobile Node uses reverse tunneling with ESP
+ encryption, then the Home Address is not revealed on the MN - HA
+ path. So, eavesdroppers on the MN - HA path cannot determine
+ roaming. They could, however, still profile fields in the ESP
+ header; however, this problem is not specific to Mobile IPv6 location
+ privacy.
- When a MN uses reverse tunneling (regardless of ESP encryption),
- the correspondent does not have access to the Care-of Address.
- Hence, it cannot determine that the MN has roamed.
+ When a MN uses reverse tunneling (regardless of ESP encryption), the
+ correspondent does not have access to the Care-of Address. Hence, it
+ cannot determine that the MN has roamed.
Hence, the location privacy problem is particularly applicable when
- Mobile IPv6 route optimization is used or when reverse tunneling
- is used without protecting the inner IP packet containing the Home
+ Mobile IPv6 route optimization is used or when reverse tunneling is
+ used without protecting the inner IP packet containing the Home
Address.
4. Problem Illustration
This section is intended to provide an illustration of the problem
defined in the previous section.
- Consider a Mobile Node at its home network. Whenever it is
- involved in IP communication, its correspondents can see an
- IP address valid on the home network. Elaborating further,
- the users involved in peer - peer communication are likely
- to see a user-friendly identifier such as a SIP URI, and the
- communication end-points in the IP stack will see IP addresses.
- Users uninterested in or unaware of IP communication details will
- not see any difference when the MN acquires a new IP address.
- Of course any user can ``tcpdump'' or ``ethereal'' a session,
- capture IP packets and map the MN's IP address to an approximate
- geo-location. This mapping may reveal the home location of a
- user, but a correspondent cannot ascertain whether the user has
- actually roamed or not. Assessing the physical location based on
- IP addresses has some similarities to assessing the geographical
- location based on the area-code of a telephone number. The
- granularity of the physical area corresponding to an IP address
- can vary depending on how sophisticated the available tools are,
- how often an ISP conducts its network re-numbering, etc. And,
- an IP address cannot also guarantee that a peer is at a certain
- geographic area due to technologies such as VPN and tunneling.
+ Consider a Mobile Node at its home network. Whenever it is involved
+ in IP communication, its correspondents can see an IP address valid
+ on the home network. Elaborating further, the users involved in peer
+ - peer communication are likely to see a user-friendly identifier
+ such as a SIP URI, and the communication end-points in the IP stack
+ will see IP addresses. Users uninterested in or unaware of IP
+ communication details will not see any difference when the MN
+ acquires a new IP address. Of course any user can ``tcpdump'' or
+ ``ethereal'' a session, capture IP packets and map the MN's IP
+ address to an approximate geo-location. This mapping may reveal the
+ home location of a user, but a correspondent cannot ascertain whether
+ the user has actually roamed or not. Assessing the physical location
+ based on IP addresses has some similarities to assessing the
+ geographical location based on the area-code of a telephone number.
+ The granularity of the physical area corresponding to an IP address
+ can vary depending on how sophisticated the available tools are, how
+ often an ISP conducts its network re-numbering, etc. And, an IP
+ address cannot also guarantee that a peer is at a certain geographic
+ area due to technologies such as VPN and tunneling.
When the MN roams to another network, the location privacy problem
consists of two parts: revealing information to its correspondents
and to on-lookers.
- With its correspondents, the MN can either communicate directly
- or reverse tunnel its packets through the Home Agent. Using
- reverse tunneling does not reveal Care-of Address of the MN,
- although end-to-end delay may vary depending on the particular
- scenario. With those correspondents with which it can disclose its
- Care-of Address ``on the wire'', the MN has the option of using
- route-optimized communication. The transport protocol still sees
- the Home Address with route optimization. Unless the correspondent
- runs some packet capturing utility, the user cannot see which mode
- (reverse tunneling or route optimization) is being used, but knows
- that it is communicating with the same peer whose URI it knows.
- This is similar to conversing with a roaming cellphone user whose
- phone number, like the URI, remains unchanged.
+ With its correspondents, the MN can either communicate directly or
+ reverse tunnel its packets through the Home Agent. Using reverse
+ tunneling does not reveal Care-of Address of the MN, although end-to-
+ end delay may vary depending on the particular scenario. With those
+ correspondents with which it can disclose its Care-of Address ``on
+ the wire'', the MN has the option of using route-optimized
+ communication. The transport protocol still sees the Home Address
+ with route optimization. Unless the correspondent runs some packet
+ capturing utility, the user cannot see which mode (reverse tunneling
+ or route optimization) is being used, but knows that it is
+ communicating with the same peer whose URI it knows. This is similar
+ to conversing with a roaming cellphone user whose phone number, like
+ the URI, remains unchanged.
Regardless of whether the MN uses route optimization or reverse
- tunneling (without ESP encryption), its Home Address is revealed
- in data packets. When equipped with an ability to inspect packets
- ``on the wire'', an on-looker on the MN - HA path can determine
- that the MN has roamed and could possibly also determine that
- the user has roamed. This could compromise the location privacy
- even if the MN took steps to hide its roaming information from a
- correspondent.
+ tunneling (without ESP encryption), its Home Address is revealed in
+ data packets. When equipped with an ability to inspect packets ``on
+ the wire'', an on-looker on the MN - HA path can determine that the
+ MN has roamed and could possibly also determine that the user has
+ roamed. This could compromise the location privacy even if the MN
+ took steps to hide its roaming information from a correspondent.
The above description is valid regardless of whether a Home Address
- is statically allocated or is dynamically allocated. In either
- case, the mapping of IP address to geo-location will most likely
- yield results with the same level of granularity. With the freely
+ is statically allocated or is dynamically allocated. In either case,
+ the mapping of IP address to geo-location will most likely yield
+ results with the same level of granularity. With the freely
available tools on the Internet, this granularity is the physical
- address of the ISP or the organization which registers ownership of
- a prefix chunk. Since an ISP or an organization is not, rightly,
+ address of the ISP or the organization which registers ownership of a
+ prefix chunk. Since an ISP or an organization is not, rightly,
required to provide a blue-print of its subnets, the granularity
remains fairly coarse for a mobile wireless network. However,
sophisticated attackers might be able to conduct site mapping and
obtain more fine-grained subnet information.
A compromise in location privacy could lead to more targetted
- profiling of user data. An eavesdropper may specifically track
- the traffic containing the Home Address, and monitor the movement
- of the Mobile Node with changing Care-of Address. The profiling
- problem is not specific to Mobile IPv6, but could be triggered
- by a compromise in location privacy due to revealing the Home
- Address. A correspondent may take advantage of the knowledge that
- a user has roamed when Care-of Address is revealed, and modulate
- actions based on such a knowledge. Such an information could cause
- concern to a mobile user especially when the correspondent turns
- out be untrustworthy. For these reasons, appropriate management
- interfaces on the MN to guard against the misuse of location
- information should be considered.
+ profiling of user data. An eavesdropper may specifically track the
+ traffic containing the Home Address, and monitor the movement of the
+ Mobile Node with changing Care-of Address. The profiling problem is
+ not specific to Mobile IPv6, but could be triggered by a compromise
+ in location privacy due to revealing the Home Address. A
+ correspondent may take advantage of the knowledge that a user has
+ roamed when Care-of Address is revealed, and modulate actions based
+ on such a knowledge. Such an information could cause concern to a
+ mobile user especially when the correspondent turns out be
+ untrustworthy. For these reasons, appropriate security measures on
+ the management interfaces on the MN to guard against the disclosure
+ or misuse of location information should be considered.
Applying existing techniques to thwart profiling may have
implications to Mobile IPv6 signaling performance. For instance,
changing the Care-of Address often would cause additional Return
- Routability [1] and binding management signaling. And, changing
- the Home Address often has implications on IPsec security
+ Routability [rfc3775] and binding management signaling. And,
+ changing the Home Address often has implications on IPsec security
association management. Solutions should be careful in considering
the cost of change of either Care-of Address or Home Address on
signaling.
When roaming, a MN may treat its home network nodes as any other
correspondents. Reverse tunneling is perhaps sufficient for home
network communication, since route-optimized communication will
traverse the identical path. Hence, a MN can avoid revealing its
Care-of Address to its home network correspondents simply by using
- reverse tunneling. The Proxy Neighbor Advertisements [7] from the
- Home Agent could serve as hints to the home network nodes that the
- Mobile Node is away. However, they will not be able to know the
+ reverse tunneling. The Proxy Neighbor Advertisements [rfc2461] from
+ the Home Agent could serve as hints to the home network nodes that
+ the Mobile Node is away. However, they will not be able to know the
Mobile Node's current point of attachment unless the MN uses route
optimization with them.
5. Conclusion
- In this document, we have discussed the location privacy problem
- as applicable to Mobile IPv6. The problem can be summarized
- as follows: disclosing Care-of Address to a correspondent and
- revealing Home Address to an on-looker can compromise the location
- privacy of a Mobile Node, and hence that of a user. We have seen
- that bidirectional tunneling allows a MN to protect its Care-of
- Address to the CN. And, ESP encryption of inner IP packet allows
- the MN to protect its Home Address from the on-lookers on the MN -
- HA path. However, with route optimization, the MN will reveal its
- Care-of Address to the CN. Moreover, route optimization causes the
- Home Address to be revealed to on-lookers in the data packets as
- well as in Mobile IPv6 signaling messages. The solutions to this
- problem are expected to be protocol specifications assuming the
- existing Mobile IPv6 functional entities, namely, the Mobile Node,
- its Home Agent and the Correspondent Node.
+ In this document, we have discussed the location privacy problem as
+ applicable to Mobile IPv6. The problem can be summarized as follows:
+ disclosing Care-of Address to a correspondent and revealing Home
+ Address to an on-looker can compromise the location privacy of a
+ Mobile Node, and hence that of a user. We have seen that
+ bidirectional tunneling allows a MN to protect its Care-of Address to
+ the CN. And, ESP encryption of inner IP packet allows the MN to
+ protect its Home Address from the on-lookers on the MN - HA path.
+ However, with route optimization, the MN will reveal its Care-of
+ Address to the CN. Moreover, route optimization causes the Home
+ Address to be revealed to on-lookers in the data packets as well as
+ in Mobile IPv6 signaling messages. The solutions to this problem are
+ expected to be protocol specifications assuming the existing Mobile
+ IPv6 functional entities, namely, the Mobile Node, its Home Agent and
+ the Correspondent Node.
6. IANA Considerations
There are no IANA considerations introduced by this draft.
7. Security Considerations
This document discusses the location privacy problem specific to
Mobile IPv6. Any solution must be able to protect (e.g., using
- encryption) the Home Address from disclosure to on-lookers in
- data packets when using route optimization or reverse tunneling.
- In addition, solutions must consider protecting the Mobile IPv6
- signaling messages from disclosing the Home Address along the MN -
- HA and MN - CN paths.
+ encryption) the Home Address from disclosure to on-lookers in data
+ packets when using route optimization or reverse tunneling. In
+ addition, solutions must consider protecting the Mobile IPv6
+ signaling messages from disclosing the Home Address along the MN - HA
+ and MN - CN paths.
- Disclosing the Care-of Address is inevitable if a MN wishes to
- use route optimization. Regardless of whether Care-of Address
- is an on-link address of the MN on the visited link or that of
- a co-operating proxy, mere presence of Binding Cache entry is
- sufficient for a CN to ascertain roaming. Hence, a MN concerned
- with location privacy should exercise prudence in determining
- whether to use route optimization with, especially previously
- unacquainted, correspondents.
+ Disclosing the Care-of Address is inevitable if a MN wishes to use
+ route optimization. Regardless of whether Care-of Address is an on-
+ link address of the MN on the visited link or that of a co-operating
+ proxy, mere presence of Binding Cache entry is sufficient for a CN to
+ ascertain roaming. Hence, a MN concerned with location privacy
+ should exercise prudence in determining whether to use route
+ optimization with, especially previously unacquainted,
+ correspondents.
- The solutions should also consider the use of temporary addresses
- and their implications on Mobile IPv6 signaling as discussed in
- Section 4. Use of IP addresses with privacy extensions [6] could
- be especially useful for Care-of Addresses if appropriate tradeoffs
- with Return Routability signaling are taken into account.
+ The solutions should also consider the use of temporary addresses and
+ their implications on Mobile IPv6 signaling as discussed in Problem
+ Illustration. Use of IP addresses with privacy extensions [rfc3041]
+ could be especially useful for Care-of Addresses if appropriate
+ tradeoffs with Return Routability signaling are taken into account.
8. Acknowledgment
- Thanks to James Kempf, Qiu Ying, Sam Xia and Lakshminath Dondeti
- for the review and feedback. Thanks to Jari Arkko and Kilian
- Weniger for the last call review and for suggesting improvements
- and text.
+ James Kempf, Qiu Ying, Sam Xia and Lakshminath Dondeti are
+ acknowledged for their review and feedback. Thanks to Jari Arkko and
+ Kilian Weniger for the last call review and for suggesting
+ improvements and text. Thanks to Sam Hartman for providing text to
+ improve the problem scope.
9. References
9.1. Normative References
- [1] D. Johnson, C. Perkins, and J. Arkko. Mobility Support in
- IPv6. Request for Comments 3775, Internet Engineering Task
- Force, June 2004.
+ [rfc3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
+ in IPv6", RFC 3775, June 2004,
+ .
9.2. Informative References
- [2] T. Berners-Lee, R. Fielding, and L. Masinter. Uniform Resource
- Identifiers (URI): Generic Syntax. Request for Comments (Draft
- Standard) 2396, Internet Engineering Task Force, August 1998.
+ [draft-haddad]
+ Haddad, W. et al., "Privacy for Mobile and Multi-homed
+ Nodes: MoMiPriv Problem Statement (work in progress)",
+ October 2004.
- [3] W. Haddad and et al., Privacy for Mobile and Multi-homed
- Nodes: MoMiPriv Problem Statement (work in progress).
- Internet Draft, Internet Engineering Task Force, October 2004.
+ [rfc1035] Mockapetris, P., "Domain names - implementation and
+ specification", RFC 1035, November 1987,
+ .
- [4] S. Kent and K. Seo. Security Architecture for the Internet
- Protocol. Request for Comments (Proposed Standard) 4301,
- Internet Engineering Task Force, December 2005.
+ [rfc2396] Berners-Lee, T., Fielding, R., and L. Manister, "Uniform
+ Resource Identifiers (URI): Generic Syntax", RFC 2396,
+ August 1998, .
- [5] P. V. Mockapetris. Domain names - implementation and
- specification. Request for Comments (Standard) 1035, Internet
- Engineering Task Force, November 1987.
+ [rfc2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor
+ Discovery for IP Version 6 (IPv6)", RFC 2461,
+ December 1998, .
- [6] T. Narten and R. Draves. Privacy Extensions for Stateless
- Address Autoconfiguration in IPv6. Request for Comments 3041,
- Internet Engineering Task Force, January 2001.
+ [rfc2462] Thomson, S. and T. Narten, "IPv6 Stateless Address
+ Autoconfiguration", RFC 2462, December 1998,
+ .
- [7] T. Narten, E. Nordmark, and W. Simpson. Neighbor Discovery for
- IP Version 6 (IPv6). Request for Comments (Draft Standard)
- 2461, Internet Engineering Task Force, December 1998.
+ [rfc3041] Narten, T. and R. Draves, "Privacy Extensions for
+ Stateless Address Autoconfiguration in IPv6", RFC 3041,
+ January 2001, .
- [8] J. Polk, J. Schnizlein, and M. Linsner. DHCP Option for
- Coordinate-based Location Configuration Information. Request
- for Comments 3825, Internet Engineering Task Force, July 2004.
+ [rfc3261] Rosenberg, J. et al., "SIP: Session Initiation
+ Protocol", RFC 3261, July 2004,
+ .
- [9] J. Rosenberg and et al. SIP: Session Initiation Protocol.
- Request for Comments (Proposed Standard) 3261, Internet
- Engineering Task Force, June 2002.
+ [rfc3825] Polk, J. and J. Schnizlein, "DHCP Option for Coordinate-
+ based Location Configuration Information", RFC 3825,
+ July 2004, .
- [10] S. Thomson and T. Narten. IPv6 Stateless Address
- Autoconfiguration. Request for Comments (Draft Standard) 2462,
- Internet Engineering Task Force, December 1998.
+ [rfc4301] Kent, S. and K. Seo, "Security Architecture for the
+ Internet Protocol", RFC 4301, December 2005,
+ .
- 10. Author's Address
+Appendix A. Background
+
+ The location privacy topic is broad and often has different
+ connotations. It also spans multiple layers in the OSI reference
+ model. Besides, there are attributes beyond an IP address alone that
+ can reveal hints about location. For instance, even if a
+ correspondent is communicating with the same end-point it is used to,
+ the ``time of the day'' attribute can reveal a hint to the user.
+ Some roaming cellphone users may have noticed that their SMS messages
+ carry a timestamp of their ``home network'' timezone (for location
+ privacy or otherwise) which can reveal that the user is in a
+ different timezone when messages are sent during ``normal'' time of
+ the day. Furthermore, tools exist on the Internet which can map an
+ IP address to the physical address of an ISP or the organization
+ which owns the prefix chunk. Taking this to another step, with in-
+ built GPS receivers on IP hosts, applications can be devised to map
+ geo-locations to IP network information. Even without GPS receivers,
+ geo-location can also be obtained in environments where "Geopriv" is
+ supported, for instance as a DHCP option [rfc3825]. In summary, a
+ user's physical location can be determined or guessed with some
+ certainty and with varying levels of granularity by different means
+ even though IP addresses themselves do not inherently provide any
+ geo-location information. It is perhaps useful to bear this broad
+ scope in mind as the problem of IP address location privacy in the
+ presence of IP Mobility is addressed.
+
+Author's Address
Rajeev Koodli
Nokia Research Center
975 Page Mill Road, 200
- Palo Alto, CA 94034 USA
- Phone: +1 408 425 6684
- Fax: +1 650 625 2502
- E-Mail: Rajeev.Koodli@nokia.com
+ Palo Alto, CA 94304
+ USA
- A. Background
+ Email: rajeev.koodli@nokia.com
- The location privacy topic is broad and often has different
- connotations. It also spans multiple layers in the OSI reference
- model. Besides, there are attributes beyond an IP address alone
- that can reveal hints about location. For instance, even if a
- correspondent is communicating with the same end-point it is used
- to, the ``time of the day'' attribute can reveal a hint to the
- user. Some roaming cellphone users may have noticed that their SMS
- messages carry a timestamp of their ``home network'' timezone (for
- location privacy or otherwise) which can reveal that the user is in
- a different timezone when messages are sent during ``normal'' time
- of the day. Furthermore, tools exist on the Internet which can map
- an IP address to the physical address of an ISP or the organization
- which owns the prefix chunk. Taking this to another step, with
- in-built GPS receivers on IP hosts, applications can be devised
- to map geo-locations to IP network information. Even without GPS
- receivers, geo-location can also be obtained in environments where
- [Geopriv] is supported, for instance as a DHCP option [8].
+Full Copyright Statement
- In summary, a user's physical location can be determined or
- guessed with some certainty and with varying levels of granularity
- by different means even though IP addresses themselves do not
- inherently provide any geo-location information. It is perhaps
- useful to bear this broad scope in mind as the problem of IP
- address location privacy in the presence of IP Mobility is
- addressed.
+ Copyright (C) The IETF Trust (2007).
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